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the highest probability to get seriously injured. Compared with the people on the second floor, people
on the first floor were undergone severer damage because they were crushed by the second floor and
the roof. Compared with the people on the right side, people on the left side got severer damage
because the structure collapsed to the left side as it can be seen in FIG.6.1.
CaseB
The structure behavior in Case B is shown in Fig.6.3. The structure started tilling at 7.6 second and
completely collapsed at 12.4 second. The computed values of Chest-G, HOC, and the human damage
level are shown in Table 6.1 (b). In this case, joint elements are considered, but the joint strength of the
first floor is half of the second floor. Therefore, only the first floor collapsed and the second floor stood
still. Because the second floor remained without collapse, the people on the second floor did not get
injured and the damage levels are 'AAA 1 or 'AA'. Both Chest-G and HEC is lower than its allowance
level. However, the people on the first floor get injured because they are affected by the crush of the
second floor. Especially, No.3 and No.4 are on the worst damage level 'D' and are expected to get
seriously injured because the structure collapsed to the right side.
CaseC
The structure behavior in Case C is shown in Fig6.4. Because the joints were strong enough to sustain
the input ground motion, the structure swayed but did not collapsed. The computed values of Chest-G,
HIC, and the human damage level are shown in Table 6.1 (c). In this case, joints have the sufficient
strength. Therefore, the structure did not collapse and nobody got injured. All people are on the safest
level 'AAA 1 . Compared to the people on the first floor, the criteria of the people on the second floor are
a little bit larger. This is because the structure was swaying during the earthquake and the second floor
was swayed more than the first floor.
CONCLUSION
Collapsing process of wooden house has been simulated by DEM, and the damage to the human body
also has been estimated. The collapsing pattern and the extent of the damage vary depends on the joint
strength. Joint elements are introduced and the influence of the joint strength has been discussed as
well. As the collapsing process of the structure is strongly affected by the spring constant and damping
coefficients in DEM, it is very important to evaluate the actual restoring force and damping force of
the wooden house, and to try to simulate a more realistic failure behavior of the structure using
parametric studies. In this study, human body has been modeled as a circle element. We have to make a
more hurnan-like model if we want to obtain detailed damage to each body part.
REFERENCES
Cundall, P. A (1974). Rational Design of Tunnel Supports - A Computer Model for Rock Mass
Behavior Using Interactive Graphics for the Input and Output of Geometrical Data. Technical Report
MRD-2-74, Missouri River Division, U.S. Army Corps of Engineers
National Organization for Automotive Safety & Victims' Aid (2001). New Car Assessment Japan